linux-toradex.git/arch/x86/kernel, branch v3.8.2

x86: Make sure we can boot in the case the BDA contains pure garbage

2013-03-03T22:03:34+00:00

commit 7c10093692ed2e6f318387d96b829320aa0ca64c upstream.

On non-BIOS platforms it is possible that the BIOS data area contains
garbage instead of being zeroed or something equivalent (firmware
people: we are talking of 1.5K here, so please do the sane thing.)

We need on the order of 20-30K of low memory in order to boot, which
may grow up to < 64K in the future.  We probably want to avoid the
lowest of the low memory.  At the same time, it seems extremely
unlikely that a legitimate EBDA would ever reach down to the 128K
(which would require it to be over half a megabyte in size.)  Thus,
pick 128K as the cutoff for "this is insane, ignore."  We may still
end up reserving a bunch of extra memory on the low megabyte, but that
is not really a major issue these days.  In the worst case we lose
512K of RAM.

This code really should be merged with trim_bios_range() in
arch/x86/kernel/setup.c, but that is a bigger patch for a later merge
window.

Reported-by: Darren Hart 
Signed-off-by: H. Peter Anvin 
Cc: Matt Fleming 
Link: http://lkml.kernel.org/n/tip-oebml055yyfm8yxmria09rja@git.kernel.org
Signed-off-by: Greg Kroah-Hartman

x86/apic: Fix parsing of the 'lapic' cmdline option

2013-03-03T22:03:33+00:00

commit 27cf929845b10043f2257693c7d179a9e0b1980e upstream.

Including " lapic " in the kernel cmdline on an x86-64 kernel
makes it panic while parsing early params -- e.g. with no user
visible output.

Fix this bug by ensuring arg is non-NULL before passing it to
strncmp().

Reported-by: PaX Team 
Signed-off-by: Mathias Krause 
Acked-by: David Rientjes 
Cc: Suresh Siddha 
Link: http://lkml.kernel.org/r/1361303227-13174-1-git-send-email-minipli@googlemail.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

x86: Hyper-V: register clocksource only if its advertised

2013-02-28T13:38:29+00:00

commit 32068f6527b8f1822a30671dedaf59c567325026 upstream.

Enable hyperv_clocksource only if its advertised as a feature.
XenServer 6 returns the signature which is checked in
ms_hyperv_platform(), but it does not offer all features. Currently the
clocksource is enabled unconditionally in ms_hyperv_init_platform(), and
the result is a hanging guest.

Hyper-V spec Bit 1 indicates the availability of Partition Reference
Counter.  Register the clocksource only if this bit is set.

The guest in question prints this in dmesg:
 [    0.000000] Hypervisor detected: Microsoft HyperV
 [    0.000000] HyperV: features 0x70, hints 0x0

This bug can be reproduced easily be setting 'viridian=1' in a HVM domU
.cfg file. A workaround without this patch is to boot the HVM guest with
'clocksource=jiffies'.

Signed-off-by: Olaf Hering 
Link: http://lkml.kernel.org/r/1359940959-32168-1-git-send-email-kys@microsoft.com
Signed-off-by: K. Y. Srinivasan 
Signed-off-by: H. Peter Anvin 
Signed-off-by: Greg Kroah-Hartman

x86/apic: Work around boot failure on HP ProLiant DL980 G7 Server systems

2013-02-11T10:13:00+00:00

When a HP ProLiant DL980 G7 Server boots a regular kernel,
there will be intermittent lost interrupts which could
result in a hang or (in extreme cases) data loss.

The reason is that this system only supports x2apic physical
mode, while the kernel boots with a logical-cluster default
setting.

This bug can be worked around by specifying the "x2apic_phys" or
"nox2apic" boot option, but we want to handle this system
without requiring manual workarounds.

The BIOS sets ACPI_FADT_APIC_PHYSICAL in FADT table.
As all apicids are smaller than 255, BIOS need to pass the
control to the OS with xapic mode, according to x2apic-spec,
chapter 2.9.

Current code handle x2apic when BIOS pass with xapic mode
enabled:

When user specifies x2apic_phys, or FADT indicates PHYSICAL:

1. During madt oem check, apic driver is set with xapic logical
   or xapic phys driver at first.

2. enable_IR_x2apic() will enable x2apic_mode.

3. if user specifies x2apic_phys on the boot line, x2apic_phys_probe()
   will install the correct x2apic phys driver and use x2apic phys mode.
   Otherwise it will skip the driver will let x2apic_cluster_probe to
   take over to install x2apic cluster driver (wrong one) even though FADT
   indicates PHYSICAL, because x2apic_phys_probe does not check
   FADT PHYSICAL.

Add checking x2apic_fadt_phys in x2apic_phys_probe() to fix the
problem.

Signed-off-by: Stoney Wang 
[ updated the changelog and simplified the code ]
Signed-off-by: Yinghai Lu 
Cc: stable@kernel.org
Link: http://lkml.kernel.org/r/1360263182-16226-1-git-send-email-yinghai@kernel.org
Signed-off-by: Ingo Molnar

Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2013-02-04T20:59:44+00:00

Pull x86 fixes from Ingo Molnar:
 "Three small fixlets"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/intel/cacheinfo: Shut up annoying warning
  x86, doc: Boot protocol 2.12 is in 3.8
  x86-64: Replace left over sti/cli in ia32 audit exit code

Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2013-02-04T20:57:09+00:00

Pull perf fixes from Ingo Molnar:
 "Three fixlets and two small (and low risk) hw-enablement changes"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf: Fix event group context move
  x86/perf: Add IvyBridge EP support
  perf/x86: Fix P6 driver section warning
  arch/x86/tools/insn_sanity.c: Identify source of messages
  perf/x86: Enable Intel Lincroft/Penwell/Cloverview Atom support

x86/intel/cacheinfo: Shut up annoying warning

2013-02-04T10:29:52+00:00

I've been getting the following warning when doing randbuilds
since forever. Now it finally pissed me off just the perfect
amount so that I can fix it.

  arch/x86/kernel/cpu/intel_cacheinfo.c:489:27: warning: ‘cache_disable_0’ defined but not used [-Wunused-variable]
  arch/x86/kernel/cpu/intel_cacheinfo.c:491:27: warning: ‘cache_disable_1’ defined but not used [-Wunused-variable] arch/x86/kernel/cpu/intel_cacheinfo.c:524:27: warning: ‘subcaches’ defined but not used [-Wunused-variable]

It happens because in randconfigs where CONFIG_SYSFS is not set,
the whole sysfs-interface to L3 cache index disabling is
remaining unused and gcc correctly warns about it. Make it
optional, depending on CONFIG_SYSFS too, as is the case with
other sysfs-related machinery in this file.

Signed-off-by: Borislav Petkov 
Cc: Andreas Herrmann 
Link: http://lkml.kernel.org/r/1359969195-27362-1-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar

Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2013-01-31T06:08:43+00:00

Pull x86 fixes from Peter Anvin:
 "This is a collection of miscellaneous fixes, the most important one is
  the fix for the Samsung laptop bricking issue (auto-blacklisting the
  samsung-laptop driver); the efi_enabled() changes you see below are
  prerequisites for that fix.

  The other issues fixed are booting on OLPC XO-1.5, an UV fix, NMI
  debugging, and requiring CAP_SYS_RAWIO for MSR references, just as
  with I/O port references."

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  samsung-laptop: Disable on EFI hardware
  efi: Make 'efi_enabled' a function to query EFI facilities
  smp: Fix SMP function call empty cpu mask race
  x86/msr: Add capabilities check
  x86/dma-debug: Bump PREALLOC_DMA_DEBUG_ENTRIES
  x86/olpc: Fix olpc-xo1-sci.c build errors
  arch/x86/platform/uv: Fix incorrect tlb flush all issue
  x86-64: Fix unwind annotations in recent NMI changes
  x86-32: Start out cr0 clean, disable paging before modifying cr3/4

efi: Make 'efi_enabled' a function to query EFI facilities

2013-01-30T19:51:59+00:00

Originally 'efi_enabled' indicated whether a kernel was booted from
EFI firmware. Over time its semantics have changed, and it now
indicates whether or not we are booted on an EFI machine with
bit-native firmware, e.g. 64-bit kernel with 64-bit firmware.

The immediate motivation for this patch is the bug report at,

    https://bugs.launchpad.net/ubuntu-cdimage/+bug/1040557

which details how running a platform driver on an EFI machine that is
designed to run under BIOS can cause the machine to become
bricked. Also, the following report,

    https://bugzilla.kernel.org/show_bug.cgi?id=47121

details how running said driver can also cause Machine Check
Exceptions. Drivers need a new means of detecting whether they're
running on an EFI machine, as sadly the expression,

    if (!efi_enabled)

hasn't been a sufficient condition for quite some time.

Users actually want to query 'efi_enabled' for different reasons -
what they really want access to is the list of available EFI
facilities.

For instance, the x86 reboot code needs to know whether it can invoke
the ResetSystem() function provided by the EFI runtime services, while
the ACPI OSL code wants to know whether the EFI config tables were
mapped successfully. There are also checks in some of the platform
driver code to simply see if they're running on an EFI machine (which
would make it a bad idea to do BIOS-y things).

This patch is a prereq for the samsung-laptop fix patch.

Cc: David Airlie 
Cc: Corentin Chary 
Cc: Matthew Garrett 
Cc: Dave Jiang 
Cc: Olof Johansson 
Cc: Peter Jones 
Cc: Colin Ian King 
Cc: Steve Langasek 
Cc: Tony Luck 
Cc: Konrad Rzeszutek Wilk 
Cc: Rafael J. Wysocki 
Cc: 
Signed-off-by: Matt Fleming 
Signed-off-by: H. Peter Anvin

x86/msr: Add capabilities check

2013-01-24T16:37:51+00:00

At the moment the MSR driver only relies upon file system
checks. This means that anything as root with any capability set
can write to MSRs. Historically that wasn't very interesting but
on modern processors the MSRs are such that writing to them
provides several ways to execute arbitary code in kernel space.
Sample code and documentation on doing this is circulating and
MSR attacks are used on Windows 64bit rootkits already.

In the Linux case you still need to be able to open the device
file so the impact is fairly limited and reduces the security of
some capability and security model based systems down towards
that of a generic "root owns the box" setup.

Therefore they should require CAP_SYS_RAWIO to prevent an
elevation of capabilities. The impact of this is fairly minimal
on most setups because they don't have heavy use of
capabilities. Those using SELinux, SMACK or AppArmor rules might
want to consider if their rulesets on the MSR driver could be
tighter.

Signed-off-by: Alan Cox 
Cc: Linus Torvalds 
Cc: Andrew Morton 
Cc: Peter Zijlstra 
Cc: Horses 
Signed-off-by: Ingo Molnar